A number of methods are available to alkylate phenols with alpha-branched alkyl groups. For example, the reaction of an olefin, such as propylene, isobutylene or butene, with phenol in the presence of an acid catalyst leads to a mixture of alpha-branched alkylphenols. In another method, described in U.S. Pat. No. 2,831,898, an aluminum phenoxide catalyst is employed which leads to selective orthoalkylation of the phenol. In either case, it frequently occurs that some of the coponents in the product mixture contain more alkyl groups than desired or have the alkyl groups substituted in the wrong position. For example, in the alkylation of phenol with butene using an aluminum phenoxide catalyst the product in greatest demand is generally o-sec-butyl-phenol. This is an intermediate in the production of 2,4-di-nitro-6-sec-butylphenol, a valuable selective herbicide. In the aluminum phenoxide catalyzed alkylation of phenol to prepare o-sec-butylphenol some polyalkylation occurs leading to, for example, 2,6-di-sec-butylphenol. In the past, unless some market could be found, the 2,6-di-sec-butylphenol was either discarded or, at best, subjected to a separate dealkylation process such as described by Kolka et al., J. Org. Chem., 22, 1957, or in British Pat. No. 940,378. The Kolka et al. dealkylation process is shown to be applicable to ortho-tert-butylphenol and the British Pat. No. 940,378 dealkylation process is said to be applicable to para alkylphenols. These methods of recovering phenol valve not only require a separate process step but also result in loss of dealkylated olefin.
Other related processes which are acknowledged are U.S. Pat. No. 3,418,380 disclosing transalkylation of tert-butyl groups employing a sulfuric acid catalyst. Dealkylation of 4,6-di-tert-alkyl-m-cresol using an aluminum phenoxide catalyst is disclosed in U.S. Pat. No. 3,091,646. Transalkylation of p-cresol by 2,6-di-tert-butyl-p-cresol using a polystyrene sulfonic acid catalyst is disclosed in U.S. Pat. No. 2,802,884. Other pertinent prior art is U.S. Pat. No. 2,578,597; U.S. Pat. No. 3,417,149; U.S. Pat No. 3,519,692; British Pat. No. 776,204 and British Pat. No. 1,062,298. Accordingly, a need exists for a process that can convert di-ortho-sec-alkylated phenols co-produced in alkylation processes to lower alkylated phenols and, at the same time, transfer the ortho-sec-alkyl group removed from the di-alkylated phenol to another phenolic compound to yield a more desirable product.